Crowning attachment for gear finishing machines



Nov. 14, 1944, B, I WARD ET AL 2,362,785

cnowume ATTACHMENT FOR GEAR FINISHING MACHINES Filed July 1} 1941 2 Sheets-Sheet 1 EEIIigg M" Nov. 14, 1944. 5.1. WARD m;

CROWNING ATTACHMENT FOR GEAR FINISHING MACHINES Filed July 1, 19 41 2 Sheets-Sheet 2 IIIIIIIHIIIH HIIHIJ III I Mia machine shown in Fig. 2as

Patented Nov. 14, 1944' CROWNING ATTACHMENT FOR GEAR FINISHING MACHINES Bernard L. Ward and DonaldG. Weatherup, Springfield, Vt., assignors to The Fellows Gear Shap'er Company, Springfield, Vt., a corporation of Vermont -Application July 1, 1941, Serial No. 400,628

(01. Elli-4.6)

22 claims.

This invention is concerned with machines for finishing gears by shaving, lapping or analogous operations, and with provisions for effecting an inclination between the axis of the Work gear and the path of relative operating travelbetween the work gear and finishing. tool to produce a crowned effect in the work. In the operation of machines of the type referred to, the relative travel in the directionof the axis of the work piece, when combined with rotation of the tool and'work in pressure contact, causes metal to be removed from the faces of the gear teeth; and the tilting of the work gear to inclinations of opposite I handsor different degrees, in the course of the relative traversing'movement, causes the finished teeth to have greater thickness in some parts of their length than ineother parts. In other words,

between the work axis and path of relative traverse rapidly (in proportion to the time required for relative traverse of the tool along the entire length of the gear), and a-related phase has been to enable the point at which such reversal takes place to be readily'changed and adjusted.

An illustrative embodiment of means by which these objects are attained is set forth' in the -following specification anddescribed in the accompanying drawings; The said embodiment, and all substantial equivalents thereof containing the same principles constitute the invention.

In'the drawingsr Fig. I is a plan view, partly diagrammatic, of

a gear finishing machine with which have been combined appliances containing this invention for causingthe' gears to be crowned finishing;

Fig. 2 is a partial front elevation of the machine'showing the mechanism by which angular movement is imparted to the work table ofthe machine; I

Fig. 3 is an end elevation of the parts of the viewed from the left of Fig.2}

. Figs. 4 t me are sectionalviews taken on lines in course of 4-4 and 5-5, respectively, on a larger scale;

Fig. 6 is a sectional view taken on line 6-6 of Fi a Fig. 7 is a diagrammatic sectional view illustratingv the manner in which the work gear is tilted with respect to the tool by means of the herein illustrated embodiment of the invention; 2 Fig. 8 is a detail sectional view of one of the gear teeth crowned by the meansdescribed, said view being a section on line B8 of Fig. '7 on a larger scale and with exaggeration of the crowning effect.

Like reference characters designate the same of Fig. 2 and shown parts wherever they occur in all the figures.

the work gear is supported by and between alined centers I and 2 projecting toward one another from a head stock 3 and. tail stock 4, which are 1 secured to a table 5 mounted on the base 6 of the machine. The tool T, which may be a gear shaving tool of well known character having teeth'similar to gear teeth conjugate to thework gear, or maybe a gear-shaped lapping tool or analogous tool, is mounted in a turret l on a carriage 8 guided to move in a rectilinear horizontal path in guideways provided on a depth .feed slide Ill. The turret l is adjustable angularly about a horizontal axis intersecting the axis of the tool, preferably between the ends of the .tool, in order to permit meshing of tools having helical teeth of various helix angles, or spur teeth, with spur gears or helical gears of various helix angles. Clamps ll mounted on the carriage secure the turret in its various adjustments. A shaft 12 supported in bearings in the turret 'l carries and rotates tool T in position to mesh with a work gear mounted on the centers I and 2. The means for driving shaft'lZ and for advancing the depth feed slide Ill so as to feed the tool progressively to full prescribedv depth as material i gradually removed from. the work, form no part of this invention and aretherefore not'shown 'here. They may, however, be the same; as those shown in full detail inthe aforesaid Miller application. g

. The carriage is'reciprocated by means of a screw l3 engaging a nut secured to the car'- riag e; the screw being rotated in alternately opposite directions by a reversible electric motor [5 through a pinion and face gear couple IS, a train of changeable gears ll, a shaft [8 and a pinion and face gear couple IQ, of which the face gear element is secured to screw IS.

The table 5is supported on the base 6 with provisions for sliding movement, but is coupled to the base by a pivot which limits displacements of the table to angular movements about the axis of the pivot. In this machine the table is supported in a horizontal plane and the pivot axis i vertical, and is located at one side of the tool, preferably in a plane, perpendicular to the path of the tool, which coincides with the mid position of the tool in such path; although its position may be varied. though not necessarily, the pivot axis intersects the axis of the centers I and 2. Normally the table is set with the axis of the centers I and 2 parallel to the path of reciprocation of the tool. This is the situation when gears are finished without crowning. But by swinging the table about the pivot, said axis may be inclined in either right or left convergence toward the said path in various degrees.

Provision is made for adjustment of the head and tail stocks 3 and 4' lengthwise of the table, whereby work pieces of different lengths maybe accommodated, and also the position of the work piece'with respect to the pivot axis may be varied so as to make the crowning effect symmetrical or unsymmetrical in desired degree.

The novel steps of our invention reside in a new automatic means for reversibly swinging the table about the pivot 20 and adjustably controlling the extent of swinging movement, and in the combination of such means with the essential factors of a gear finishing machine; not only the specific'maehine herein described, but others as well having different combined arrangements of work holder and tool and other means for producing the relative operating movements between tool and work.

For inclining the table we have provided a screw 2| supported by the base meshing with a nut 22 carriedby the table; In the arrangement shown the screw 2| is part of a shaft 23 supported, at one end only, by a bearing 24 in a housing 25' which is secured to the side of the base 6 adjacent to one end of the table 5. A bracket 26 is secured to the adjacent endof the table, and the nut 22 is suspended therefrom by a pivot 21, the axis-of which is per pendicular to that of the nut, whereby the latter is made self adusting to changing angularity of the table. As a convenient detail of construction, the threads of the nut are cut on two alined inserted sleeves or bushings 28 and 29 secured non rotatably in the nut and set to eliminate backlash with the screw.

It should be noted that the screw is horizontal and tangential to the path in which the nutbetween the interengaged parts and by the ca- ,7

pacity for elastic flexure of the" screw shaft,

Preferably also, al- I without causing the screw to bind in the nut or the shaft in the bearing, but it is within our contemplation to provide means well known in the art, such as a universal joint in the screw shaft, to permit deflection thereof beyond that range when our invention is used in cases involving a relatively wide divergence between the corresponding arc and tangent.

A reversible electric torque motor 30 is mounted in the housing 25 with its armature shaft 3| confined in bearings 32 and 33. A pinion 34 secured to shaft 3| meshes with a gear 35 on screw shaft 23, whereby the motor rotates the screw alternately in opposite directions. Limits to the swinging movements of the table are established by a stop screw 36 threaded through one of the walls of the housing, and a stop screw 31 threaded into an intermediate web 38 in the housing. These screws are at opposite sides of the bracket 25 in alinement with abutments 39 and 43 attached to the bracket. Lock nuts 4| and 42. on screws 36 and 311 secure the adjustments of these screws.

Reversals of the torque motor 38', as also of the carriage-propelling,motor l5, are effected by circuit changers under control of a timing member driven by the motor I25. Illustrative circuit changing and timing means, and driving mechanism therefor, are shown diagrammatically in Fig. 1. A Worm 43is connected for rotation by the. face gear element of the. pinion and face gear couple L9 previously described. As a matter .of convenient design, this worm is keyed to an extension of thecarria-ge lead screw l3. It meshe with a worm wheel 44 ona shaft 45 which, through a pinion 46 and face gear 4?, drives a timing disk or drum: 48. The: latter carries two dogs 49 and 50; spaced apart and adjustable to vary the width of the space between them, between which is located: a. projection 5! on a reciprocabl'e switch shifter 52 whichoperates reversing switches of known character in the circuit of motor i=5.- The lost motion between the dogs 49 and 50- and the projection. 51:, controlled by adjustmentof the dogs, determines the length of stroke of the carriage 8.

, A cam element 53 also is mountedon. the timing. member 48:, with. provision for angular: adjustment around the axis thereofland has a cam rise 54 acting on a switch shifter 55 which is connected to operate a reversing switch of known character'in the circuit to the torque motor 30. By suitable adjustment of the: cam member 53 reversal of the motor '30 may be caused totake place at any desired point in the travel of the carriage.

During travel of the carriage in one direction, the table-inclining screw M is. turned in right hand rotation, and during carriage: travel: in the opposite direction. it is turnedin left handrotation, with effects such as areshow-n in exaggerated. degree by Figs. 7 and 8-, where T representsthe tool, W represents the workv gear, and t represents one of theteeth of such gear. Swinging of the table occurs relatively rapidly during a relatively small proportion of the time required for full traverse of the tool, so that the side faces of. the crowned teeth exhibit a generally tapered form with arcs a and a" joining the parts of opposite taper. It is possible, by appropriate selection. of motor speed and speed reduction between the motor and. screw shaft, to cause such arcs to extend over a greater proportion. of the length. of the teeth than that shown, and even to embrace the entire tooth length.

For convenient distinction in the claims, the motor I is called the'carriage propelling motor, and the motor-39 is called the crowning motor. A torquemotor is used as the crowning-motor because it maintains a constant torque so long as it is energized, when arrested by the stop means. It isthus equally effective to tilt the table through any angle within the limits of adjustment of the stop screws 36 and 31.- But motors of othertypes, such as those driven by ex- The novel principles of the'invention are ap'- plicable to all types'of gear finishing machine whether the traversing movement isimparted to the tool or to the work gear; and whether the tool or the gear is shifted toward the other for depth feeding, Machines ,of all such types are known. The relationship of the various-parts of the machineito the vertical and horizontal is not a limiting factor of the invention, but the v principles thereof may applied in any relationship by whichlike or equivalent results are secured.

What we claim and desire to secure by Letters Patent is: 1. A gear finishing machine comprising a supporting structure, a carriage guided to travel in a fixed path on said supporting structure, a table, means on said table adapted to support rotatably a gear to be finished ora gear-like finishing tool, the'table being pivotally mounted to swing in a manner to place the axis of said supporting means and said pathin parallelism and at opposite relative inclinations, a reversible motor in driving connection with said carriage to reciprocate it in said path, a reversible crowning motor in driving engagement with said table for swinging the latter about its pivot in relatively opposite directions when rotated in opposite directions respectively, adjustable means for arresting the i swinging movement of the table, and correlated timing means organized to reverse the direction of running of both motors.

2. A gear finishing machine comprising a sup- I porting structure, a' carriage guided to travel in a fixed path on said supporting structure, a table, means on said table adapted to support rotatably a gear to be finished or a gear-like finishing" tool, the table being pivotally mounted to swing in a manner to place the axis of said supporting means and said path in parallelism and at onposite relative inclinations, a reversible motor in driving connection with said carriage to reciprocate it in said path, a reversible crowning motor in driving engagement with said table for swinging the latter about its pivot, timing means driven by the first named motor for reversing the same when the carriage has traveled a predetermined distance in each direction, associated timing means for reversing the direction of the crowning motor at apredetermined point in each passage of the carriage, and stop means associated with the table'for limiting the extent of swinging movement thereof.

about an axis transverse to the path of carriage reciprocation, supporting centers mounted on said table adapted to support a work gear rotatably and so arranged on the table that swinging movement of the latter is enabled to place the aXis of the centers parallel, and at opposite inclinations,

to said :path, adjustable stop means arranged to limit swinging movement of the. table in both directions, a reversible torque motor in driving connection with said table for swinging the latter back and forth between the limits established by said stop means, and timing means organized to cause reversal of said torque motor uponv the arrival of the-carriage at predetermined points in the courseof its travel in opposite directions.

,4. In a gear finishing machine, a supporting structure, a table on said structure in pivotal connection therewith for swinging movement, a carriage mounted on the supporting structure for reciprocating movement in a path transverse to said pivot, a reversible carriage-propelling motor, transmission mechanism between said motor and carriage for propelling thelatter, timing means driven by said motor with a rate of motion proportional tothe rate of travel of the carriage,

- motor reversing means operable by said timing means and. associated with said motor for causing reversals thereof when the carriage has completed a predetermined extent of motion in both directions, a reversible crowning motor coupled with said table for imparting angular movement to the latter about its pivot connection with the base, and control means for said crowning motor operated by said timing means to cause reversals ofthe crowning motor at'predetermined times.

5. In a gear finishing and crowning machine, a, supporting structure, a gear like finishing tool mounted on said supporting structure, a table mounted on said supporting structure in pivotal engagement therewith, means on the table for holding a work gear rotatably in mesh with said tool, a screw located at a distance from said pivot connection in tangential relation thereto, a nut in meshed engagement with said screw pivotally connected with the table for imparting swinging movement to the latter when the screw is rotated, means for rotating one member of the intermeshing tool and gear couple, and reversible motive meansin driving connection with said screw automatically operative to rotate the screw while the tool and gear rotate.

6. In a gear finishing and crowning machine of the character described, a supporting structure, a

table mounted on said supporting structure in pivotal engagement therewith, a screw located at a distance from said pivot connection in tangential relation thereto, a nut in meshed engagement with said screw pivotally connected with the table for imparting swinging movement to the latter when the screw is rotated, means on said supporting structure and table for holding agear like finishing tool and a work gear in mesh together, areversible motor in driving connection about an axis, means whereby the supporting structure and table support rotatably, one a gear shaped finishing tool and the other a work gear in intermeshing relation, a nut coupled with said table on an axis substantially parallel to the axis of said swinging movement and at a distance limiting its swinging movements.

8. In a gear finishing and crowning machine of the character described, a supporting structure,

atable connected pivotally with said structure for swinging movement, a bracket carried by said table at a distance from the pivotal connection, a nut pivoted to said bracket on an axis substantially parallel to the pivot axis of the table, ad justable stops mounted on the supporting structure at opposite sides of said bracket for limiting the movements of the table, a screw rotatably mounted on the supporting structure in a line tangent to the path of the nut, and in meshed engagement with the nut, and reversible motive means coupled with said screw for rotating it in opposite directions.

9.. A gear finishing and crowning machine comprising a supporting structure, a gear-like tool conjugate to the gear to be finished, supporting means for said tool and a work gear arranged to support them rotatably in mesh, including a reciprocating carriage whereby realtive movement is efiected between the tool and gear lengthwise of the axis of the gear, and a table mounted for pivotal movement relatively to the carriage for establishing inclinations of opposite slant and different degrees between the path of the carriage and the axis of the'wo-rk, means for reciprocating the carriage, a reversible motor coupled with the table for swinging it in opposite directions, stop means for limiting the swinging movements of the table, and timing means for causing reversals of said motor at a predetermined point in the course of the traversing movements of said carriage.

10. A gear finishing machine as set forth in claim 1, in which the timing means comprises reversible switches in the circuits of the respective motors, and a timing drum rotatable reversely simultaneously with the reciprocations of the carriage and having means for shifting said switches.

11. A gear finishing machine comprising a supporting structure, a carriage guided to travel in a fixed path on said supporting structure, means on said supporting structure adapted to support rotatably a gear to befinished or a gear-like finishing tool, a reversible motor in driving connection with said carriage to reciprocate it in said path, a timing member in coupled relation with said carriage for movement in opposite directions simultaneously with the reciprocations of the carriage, dogs mounted on said timing member, and a motor reversing device having aportion extending between said dogs in position to be engaged by one dog or the other according as the timing member moves in one direction or the opposition direction. i

12. A gear finishing, machine comprising. a supporting structure, a carriage guidedto travel. in a fixed path on said supporting structure, mearislon said supporting structure adapted to support -rotatably a gear to-be finished or a gear-likefinishing tool, a reversible motor indriving connection with said carriage to reciprocate it in said path,

shifter in the circuit of said motor having a projection extending into said space.

, 13. A gear finishing machine comprising a supporting structure, a carriage guided to travel in a fixed path on said supporting structure, means on said supporting structure adapted to support rotatably a gear to be finished or a gear-like finishing tool, a reversible motor in driving connection with said carriage to reciprocate it in said path, a rotatable timing member in geared connection with said carriage for rotation in opposite directions simultaneously with the reciprocations of the carriage, dogs mounted on said timing member with a space between them, and a switch shifter in the circuit of said motor having a projection extending into said space; said dogs being adjustable to enlarge or diminish the space whereby to. adjust the length of the carriage strokes.

14. In a machine of the character described having a reciprocable carriage and an angularly movable table, one .of which is adapted to support rotatably a gear to be finished, and the other to support a gear-like finishing tool, a reversible carriage-driving motor in driving connection with the carriage, a reversible crowningmotor in driving engagement with said table for swinging the latter about its pivot axis, a rotatable timing drum driven by said carriage-driving motor simultaneously with the carriage, dogs mounted on said timing drum with a space between them, a circuit changer for the carriage-driving motor having a part projecting into the space between said dogs, a cam element carried by the timing drum, and a circuit changer for the crowning motor arranged for actuation by said cam element to reverse the crowning motor in the course of angular movement of the timing drum in each direction.

15. A gear finishing and crowning machine comprisingasupporting structure, agear-like tool conjugate to the gear to be finished, supporting means for said'tool, supporting means for a work gear, said means being arranged to support the tool and gear rotatably in mesh, one of the supporting means being a table mounted for pivotal movement about an axis transverse to the axes of both tool and work gear for establishing inclinations of opposite slant and different degrees between the tool and the axis of the work, a reversible motor coupled with the table for swinging it in opposite directions, stop means for limiting the swinging movements of the table, and timing means for causing actuations of said motor at predetermined times :in the operation of the machine.

16. A gear finishing machine comprising a base, a table having means to hold a work gear rotatably, connected pivotally with the base to swing about an axis transverse to the axis of rotation of the Work gear, cooperating stop means associated with the base and table for limiting the extent of angular movement of the table about said axis, a gear-like finishing tool supported rotatably onthe base in position to mesh with a work gear mountedas set forth, substantially in the plane in which the work gear axis is moved by angular movementof thetable about the pivotal connection thereof with the base, means for causing the finishing tool and-gear torotate while in mesh, a reversible motor,.a driving connection between said motor and said tablevfor imparting .said angular movement to the table in one direction only while the motor runs in one and the same direction, andautomati'c means for driving the motor and said driving connection alternately pivotally connected with the base to swing about an axis transverse to the axes of rotation of both the tool and the Work gear, means for, limiting the extent of angular movement of said pivotally connected support about its pivot axis, a reversible motor, a driving connection between said motor and said pivotally connected support for causing angular motion thereof about its pivot axis in one direction only'while the motor continues to run in one and the same direction, means for running the machine to cause rotation of the tool and a work gear in mesh therewith, and automatic means for reversing said motor during the running of the machine to cause changes of the angular relationship between the gear and tool alternately inopposite directions.

18. A gear finishing machine comprising a base, a tool support mounted on the base, a gear-like finishing tool held rotatably by saidtoolsupport, a work support also mounted on the base and having means for mounting a work gear'rotatably in meshwith said tool, one of said supports being pivotally connected with the base to swing about anaxis transverse to the axes of rotation of both the tool and the work gear, means for,

operating the machine to cause rotation of the tool and Work gear in mesh together, a reversible torque motor in driving connection with said pivotally mounted support for imparting angular movement "thereto, stop means located in position to limit the swinging movements of the pivotally connected support, and means for causing a v said motor to rotate in opposite directions alternately during the running of the machine.

19. A gear finishing machine comprising a base, a table supported on said base, a pivot connection betweenthe table and base about which the 1 table may swing, means on the table forsupporting a work gear rotatably with its axis of rotation transverse to and substantially intersecting the axis of said pivot connection, a gear-like finishing tool, means for supporting said tool rotatablyin mesh with such a Work gear at one side of the axis of said pivot connection, a motor in driving connection with the table for imparting angular movement thereto about said ,pivot connection, means for causing the motor to rotate alternately in opposite directions, and adjustable stop means for variably-limiting the angular movements imparted to the table by such rotation in each direction.

20. A gear finishing machine comprising a supporting structure, means on said supporting structure for holding a gear-like finishing tool rotatably, means on said supporting structure for hold-- ing a work gear rotatably in mesh with such tool, means for effecting relative working traverse between the respective holding means in a path tion with one of the machine parts comprised by the supporting structure and pivotally engaged holding means, and an abutment in fixed connection with the other of said machine parts disposed in the space between said stops in position to engage them and so limit the swinging movement of said holdingmeans,

21. A gear finishing machine comprising a supporting structure, a-carriage and a table both mounted on the supporting structure, the car riage being movable in a prescribed path and the table having means adapted to support rotatably a -work gear or a gear-like finishing tool and being pivotally engaged with the supporting structure to swing about an axis transverse to said path to place the axis of 'said supporting means parallel and at difierent inclinations to said path, means for propelling said carriage in its path, means for swinging said table about its axis of pivotal engagement with the supporting structure, spaced stops mounted on the supporting structure, and an abutment carried by the table in the space between said stops for cooperation therewith in limiting swinging movements of the table.

22. A gear finishing machine comprising a supporting structure, a carriage and a table both mounted on the supporting structure, the carriage being movable in a prescribed path and the table having means adapted to support rotatably a work gear or a gear-like finishing tool and being pivotally engaged with the supporting structure to swing about an axis transverse to said pathto place the'axis of said supporting means par- 'in the space between said stops for cooperation therewith in limiting swinging movements of the table; said stops and abutment'being relatively adjustable so as to vary the limits of swinging movement of the table.

BERNARD L. WARD. DONALD G. WEATHERUP. 

